The present invention relates generally to a device to improve the installation of anchoring devices utilizing adhesives in concrete and more specifically, to a device to roughen cored holes.
Numerous systems are known for attaching a structural member to a concrete substrate by means of an anchoring device secured by adhesive in a drilled hole. Drilling tools for making the initial hole in the concrete suffer from several disadvantages.
Carbide drill bits produce rough walled holes which maximize the attachment of the adhesive of the anchoring device within the drilled hole. Unfortunately, carbide drilled bits are subject to wear and have short usable lives.
Diamond drills, on the other hand, have enhanced wear properties. Unfortunately, diamond drills produce smooth drill holes. The resulting holding power of an adhesive in a diamond drilled hole is up to 100 percent less than the holding power of the same adhesive in a carbide drilled hole.
The present invention comprises a drilling tool for attachment to conventional drilling means, which roughens the internal surface of a pre-drilled hole to enhance attachment of an anchoring device and adhesive placed therein.
The roughening device of the present invention is tubular in shape. One end comprises a shaft for attaching to a spindle which connects a conventional drilling device, such as a hand drill, to the roughening device. The other end of the shaft is surrounded by a tubular side wall. There is a void between the shaft and the side wall which is filled by an elastomeric material. The tubular side wall is pierced by holes through which pass cutters or abraders. These cutters or abraders are positioned through the tubular side walls with the cutting or abrading end of each cutter/abrader facing the exterior surface of the tubular side wall and the opposite non-cutting end of the cutter/abrader proximate or embedded in the elastomeric material.
The roughening device of the present invention is inexpensive and provides extremely rapid roughening of the existing hole. The placement of the elastomer between the shaft and the tubular side wall results in cushioning of the device and the cutters/abraders against shock and also allows the cutters/abraders to automatically somewhat adjust for varying tolerances within the hole. In addition, as a result of the cushioning effect of the elastomer, the cutter/abrader has a longer usable life expectancy.